BRITISH NEMERTEANS, AND SOME NEW BRITISH ANNELIDS. 411 



basal joint, and a more slender distal portion. Eyes four, the anterior pair being 

 larger as well as more distant from each other than the posterior pair. The 

 colour need not be referred to further here, than by simply mentioning that the 

 dorsum is of various shades of lustrous brown, banded at intervals with belts of 

 pale iridescent blue ; while the under surface is of a deep, dark madder-brown. 

 The body dilates behind the head, attains its maximum about the anterior third, 

 and then tapers towards the tail. It is proportionally thicker than in its allies 

 (such as Castalia and Psamathe), and garnished at each side with long resplendent 

 bristle-tufts, that glance with the varied hues of the rainbow, the effect being 

 heightened by the two long hair-like cirri that stretch beyond them. The tail 

 terminates in two long slender styles, which are shorter, however, than the cirri 

 of the fourth foot from behind. Through the mouth is protruded a large pro- 

 boscis, which is unfurnished with jaws or tentacular processes ; and this assumes 

 various forms after immersion of the living animal in spirit, or when killed by 

 the salt water being impure in any degree, — sometimes being cylindrical, or pre- 

 senting a constriction between the swollen base and distal rim. 



The first four segments after the head bear modified limbs, each consisting of 

 two long cirri. As soon as the foot attains its perfect condition, it is found to be 

 distinctly biramous, thus at once demonstrating its distinction from all the 

 Hesionea except Schmarda's Cirrosyllis (Pseudosyllis, Quatref.) and (Ersted's 

 Castalia. The superior lobe, as observed in a fine spirit-preparation, consists of 

 the long superior cirrus, which has a soft articulation at its base ; an inferior 

 cirriform branch, from the upper and basal part of which spring a series of elon- 

 gated, slender, and tapering bristles, simple throughout. After attaining some 

 thickness, the shaft (Plate XV. fig. 8) is observed to be striated longitudinally, 

 and to have minute transverse touches, which, however, attain a larger develop- 

 ment in the next series. The inferior branch of the foot also consists of two por- 

 tions, a ventral cirrus, and a bristle- bearing process, from the posterior suface of 

 which the somewhat stiff fan of jointed bristles emerges. In such forms the 

 bristles of the anterior feet have shorter tips, while those of the posterior feet 

 have more elongated terminal processes. Besides, in each foot in this species 

 the terminal pieces vary in length, the shorter occurring superiorly and inferiorly, 

 or at the edges of the fan. When highly magnified .(Plate XV. fig. 7), the claw 

 at the tip of the terminal piece is seen to be somewhat faintly marked, from the 

 blocking of its curvature by a process beneath, and the serratures of the edge 

 of the process very fine, indeed scarcely distinguishable near the end. The 

 shaft of the bristle is obliquely striated towards the articulation, longitudinally 

 throughout the rest of its extent, except as usual at the pale diminished base 

 (where the striae become indistinct), and marked by a close series of transverse 

 specks or touches. The tip of this division of the foot ends in a cirriform pro- 

 longation. The jointed bristles of the inferior branch of the foot differ, as we 



